1. Field of the Invention
The present invention relates to a cleaning liquid for lithography. More particularly, the present invention relates to a cleaning liquid for lithography that enables efficient cleaning and removal of a resist film, a sacrificial film, and furthermore residue material originating from a metallic wiring layer or low dielectric constant layer produced during an etching step, without causing corrosion to corrosion-prone materials such as tungsten, copper, a low dielectric constant material, or the like. Furthermore the present invention relates to a method for forming a wiring using the cleaning liquid for lithography.
2. Related Art
A semiconductor device laminates a metallic wiring layer, a low dielectric constant layer, an insulation layer, or the like on a substrate such as a silicon wafer, and the like. This type of semiconductor device is manufactured by processing each layer using a lithography method that employs an etching process using a resist pattern as a mask.
The resist film or a temporary laminate film (termed “a sacrificial film”) used in the lithography method, and furthermore residue material originating from a metallic wiring layer or a low dielectric constant layer produced during the etching process is removed using a cleaning liquid to prevent an adverse effect on the semiconductor device, and furthermore to prevent impediment to a subsequent processing step.
In recent years, methods for forming a wiring using a damascene method have been employed in respond to advances in high-density and highly integrated semiconductor devices. Copper that is prone to undergo corrosion is used as a metallic wiring material that configures the metallic wiring layer of the semiconductor device in this type of wiring formation method. Furthermore, a low dielectric constant material (termed an “ILD material”) is used to configure the low dielectric constant layer. Advances in achieving a low dielectric constant have resulted in use of such ILD materials that are prone to undergo corrosion. Consequently, there is a need for development of a cleaning liquid that does not cause corrosion of such corrosion-prone materials when washing the substrate.
In a method for forming a wiring using a damascene method, the material used as a sacrificial film during the etching process bears an extremely strong resemblance to the configuration of an ILD material. Consequently there is a need for development of a cleaning liquid that leaves one of these strongly similar materials (the ILD material) on the device without causing corrosion while enabling efficient removal of the other material (sacrificial film).
Furthermore, in a method for forming a conventional aluminum wiring, there has been no need for high cleaning performance in a cleaning liquid since a washing process using a chemical liquid is performed after an oxygen-plasma ashing process step. However this type of oxygen-plasma ashing process cannot be used during washing of a substrate that includes a corrosion-prone material such as copper or an ILD material as described above. Consequently, there is a need for development of a cleaning liquid that has robust cleaning performance enabling complete removal of various types of residue materials even in the absence of the above type of oxygen-plasma ashing process step.
A conventional cleaning liquid for lithography used in a manufacturing process of this type of semiconductor device has been proposed that has a quaternary ammonium hydroxide as a principal component (for example, refer to Patent Documents 1 and 2). A cleaning liquid for lithography that has a quaternary ammonium hydroxide as a principal component realizes a large improvement in relation to removal performance of various types of residue materials in comparison to previous cleaning liquids, and exhibits excellent corrosion suppression performance in relation to corrosion-prone materials.
A cleaning liquid for lithography has also been proposed in which 1 mass % or less of potassium hydroxide relative to the total mass is added to a material having a quaternary ammonium hydroxide as a principal component (refer to Patent Document 3). A cleaning liquid for lithography including potassium hydroxide as described above achieves a higher level of removal performance without causing corrosion of a corrosion-prone material such as copper or an ILD material.
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2002-357908
Patent Document 2: Japanese Unexamined Patent Application, First Publication No. 2004-103771
Patent Document 3: Japanese Translation of PCT International Publication, No. 2006-527783